Updating current time…

No shared working hoursThu, Oct 15

GMT
12am
3am
6am
9am
12pm
3pm
6pm
9pm
The United Kingdom is on summer time: BST (UTC+1) until Sun, Oct 25.

Iceland and Ghana stay on GMT (UTC+0).

TOT
UTC+13
tomorrow (next day)
13h ahead
12am
3am
6am
9am
12pm
3pm
6pm
9pm

Quick answers

Selected conversion

12:00 pm12:00 GMT (UTC+0), Oct 15, 2026 = 1:00 am01:00 TOT (UTC+13), Oct 16, 2026

GMT is 13 hours behind TOT.

GMT and TOT examples

These examples always use GMT (UTC+0) and TOT (UTC+13). They stay the same when you change the date or time above. The selected conversion may differ when daylight saving time applies.

GMT is 13 hours behind TOT.

How the time difference changes

GMT is 13 hours behind TOT year-round.

Working hours of 9:00 am to 6:00 pm in GMT correspond to 10:00 pm to 7:00 am (next day) in TOT.Working hours of 09:00 to 18:00 in GMT correspond to 22:00 to 07:00 (next day) in TOT.

Compare GMT time with TOT time, including current local time, UTC offsets, time difference, daylight saving changes, working hours, and shareable meeting times.

Time Difference

Greenwich Mean Time is 13 hours behind Tonga Time.
12:00 pm12:00 in GMT is 1:00 am01:00 in TOT

GMT to TOT call time
Best time for a conference call or a meeting is between 6:30pm-7:30pm18:30-19:30 in GMT which corresponds to 7:30am-8:30am07:30-08:30 in TOT (next day). Their 9am–6pm09:00–18:00 working hours do not overlap; this is a suggested compromise.

12:00 pm12:00 Greenwich Mean Time (GMT). Offset UTC 0:00 hours
1:00 am01:00 Tonga Time (TOT). Offset UTC +13:00 hours

12:00 pm12:00 GMT / 1:00 am01:00 TOT

Choose an hour to update the converter. Day labels such as “next day” or “+1” are relative to the selected date in the first column. Use Up and Down arrow keys, Home or End to move between hours, then Enter or Space to select.

Hourly time comparison
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Greenwich Mean Time

Offset: GMT is the same as Greenwich Mean Time (GMT).

Countries using this time zone: Burkina Faso, Côte d'Ivoire, Britain (UK), Guernsey, Ghana, Greenland, Gambia, Guinea, Guinea-Bissau, Ireland, Isle of Man, Iceland, Jersey, Liberia, Mali, Mauritania, St Helena, Sierra Leone, Senegal, Sao Tome & Principe, Togo

Principal Cities: The largest city in the GMT time zone is London in the United Kingdom, with about 8.962 million people. Other major cities in this time zone include Abidjan, Bamako, Dakar, Kumasi.

Greenwich Mean Time (GMT) originally referred to the mean solar time at the Royal Observatory in Greenwich, London. It is now often used to refer to Coordinated Universal Time (UTC) when this is viewed as a time zone, and in casual use the two are the same. In the military, GMT is known as Zulu time. Greenwich Mean Time was the same as Universal Time (UT), a standard astronomical concept used in many technical fields, until the introduction of UTC in 1972.

Map of the areas on Greenwich Mean Time (GMT)
GMT all year GMT part of the year

Today the lighter areas are on UTC+1 (British Summer Time, Irish Standard Time).

GMT representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • Z - is the zone designator for the zero UTC/GMT offset, also known as 'Zulu' time
  • +00 - basic short
  • +0000 - basic
  • +00:00 - extended
Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • +0000 - sign character (+) followed by a four digit time providing hours (00) and minutes (00) of the offset. Indicates the zero UTC/GMT offset.
Military/NATO: Used by the U.S. military, Chinese military and others
  • Zulu - Military abbreviation for GMT
  • Z - short form of 'Zulu'
IANA/Olson: Reflects GMT time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • Africa/Abidjan
  • Africa/Accra
  • Africa/Bamako
  • Africa/Banjul
  • Africa/Bissau
  • Africa/Conakry
  • Africa/Dakar
  • Africa/Freetown
  • Africa/Lome
  • Africa/Monrovia
  • Africa/Nouakchott
  • Africa/Ouagadougou
  • Africa/Sao_Tome
  • Africa/Timbuktu
  • America/Danmarkshavn
  • Atlantic/Reykjavik
  • Atlantic/St_Helena
  • Eire
  • Etc/GMT
  • Etc/GMT+0
  • Etc/GMT-0
  • Etc/GMT0
  • Etc/Greenwich
  • Europe/Belfast
  • Europe/Dublin
  • Europe/Guernsey
  • Europe/Isle_of_Man
  • Europe/Jersey
  • Europe/London
  • GB
  • GB-Eire
  • GMT
  • GMT+0
  • GMT-0
  • GMT0
  • Greenwich
  • Iceland
Time zones with the GMT +0 offset:
  • EGST - Eastern Greenland Summer Time
  • GMT - Greenwich Mean Time
  • WET - Western European Time
  • AZOST - Azores Summer Time
  • UTC - Coordinated Universal Time
  • WT - Western Sahara Standard Time
  • Z - Zulu Time Zone

Tonga Time

Offset: TOT is 13 hours ahead of Greenwich Mean Time (GMT).

Countries using this time zone: Tonga

Principal Cities: The largest city in the TOT time zone is Nuku‘alofa in Tonga, with about 22,400 people. Other major cities in this time zone include Mu‘a, Neiafu, Haveluloto, Tofoa-Koloua.

Daylight Saving: Clocks in Tonga Time (TOT) do not change for daylight saving time, so TOT stays the same throughout the year. Other time zones may set clocks forward in summer and back in winter; see upcoming clock changes worldwide.

TOT representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • +13 - basic short
  • +1300 - basic
  • +13:00 - extended
Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • +1300 - sign character (+) followed by a four digit time providing hours (13) and minutes (00) of the offset. Indicates an offset of thirteen hours to the east of the zero meridian.
Time zones with the GMT +13 offset:
  • FJST - Fiji Summer Time
  • NZDT - New Zealand Daylight Time
  • PHOT - Phoenix Island Time
  • TKT - Tokelau Time
  • TOT - Tonga Time
  • WST - West Samoa Time
  • WSST - West Samoa Standard Time